From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
To Mr. Clark regarding 9 test pieces sent to Mr. Purdon, stamped H.
| Identifier | ExFiles\Box 36\3\ scan 087 | |
| Date | 24th May 1917 | |
| Mr. Clark X.3039 24.5.17. 9 test pieces sent to Mr. Purdon, stamped H! X.2746 X.3039 X.3040 | ||